Influencing Factors of Fermentation and Its Control

1, Turning Pile

Turning the pile for oxygen is one of the basic conditions for aerobic fermentation production. The main function of turning the pile is to:
① provide oxygen to accelerate the fermentation process of microorganisms; ② regulate the pile temperature; ③ dry the pile material.

Turning the pile a few times, ventilation is not enough to provide sufficient oxygen to microorganisms, affecting the rise in fermentation temperature; turning the pile more times is likely to make the heat of the pile dissipated, affecting the degree of harmless fermentation. Usually turn the pile 2-3 times during fermentation according to the situation.

2, The content of organic matter

Organic matter content affects the temperature of the pile and ventilation and oxygenation. Organic matter content is too low, the heat generated by decomposition is not enough to promote and maintain the proliferation of thermophilic bacteria in the fermentation, fertilizer pile is difficult to reach the high temperature stage, affecting the health and harmless effect of fermentation. Moreover, due to the low organic matter content, it will affect the fertilization efficiency and use value of fermented products.

The organic matter content is too high, it needs a large amount of oxygen supply, which will cause practical difficulties to the turning pile oxygen supply, there is a risk of insufficient oxygen supply, resulting in part of the anaerobic conditions. The appropriate organic matter content is 20-80%

3, C / N Ratio

The most suitable 25:1

In fermentation, organic C is mainly used as the energy material of microorganism, most of the organic C is oxidized and decomposed into CO2 and volatilized in the process of microorganism metabolism, and some C constitutes the cellular material of microorganism itself. Nitrogen is mainly consumed in protoplasm synthesis, and the most suitable C/N ratio is between 4 and 30 in terms of microbial nutrient needs. organic matter is decomposed by microorganisms at the maximum rate when the organic matter C/N ratio is around 10.

As the C/N ratio increases, the fermentation time is relatively longer. When the C/N ratio of raw materials is 20, 30 to 50, 78, the corresponding required fermentation time is about 9 to 12 days, 10 to 19 days, and 21 days, but when the C/N ratio is greater than 80:1, the fermentation is difficult.

The C/N ratio of each fermented raw material is usually 300~1000 for sawdust chips, 70~100 for straw, 50~80 for raw materials, 6~10 for human manure, 8~26 for cow manure, 7~15 for pig manure, 5~10 for chicken manure, and 8~15 for sewage sludge.

After pile rotting C / N ratio will be significantly lower than before pile rotting, usually in 10 ~ 20:1, this C / N ratio of decomposition and fermentation, agricultural use of fertilizer effect is better.

4, Water

Whether the moisture is appropriate directly affects the fermentation and fermentation speed and degree of decay. For sludge fermentation, the appropriate moisture content of the pile is 55-65%. In practice, a simple method of measurement is to hold the material tightly in hand to form a ball, and water traces appear, but water does not drip out as appropriate. The most suitable moisture for raw material fermentation is 55%.

5, Granularity

The oxygen needed for fermentation is supplied through the pores of fermented raw material particles. Porosity and pore size depends on the particle size and structural strength, like paper, plants and animals, fiber fabrics, etc., when water pressure will increase the density, the pores between the particles greatly reduced, not conducive to ventilation and oxygen supply. The suitable size of particles is generally 12-60mm.

6, pH

Microorganisms can reproduce in a wide range of pH, the suitable pH is 6-8.5. pH value usually does not need to be adjusted during fermentation.